Why does the Mishnah say "these are the words of R'Yehudah? No other opinion is quoted.
Noach miTelshestone, Israel
The Rambam in Perush ha'Mishnah actually writes that the Halachah does not follow Rebbi Yehudah. He clearly understands that someone is arguing on Rebbi Yehudah, even if he is not cited in the Mishnah. The Radvaz (Hilchos Nedarim 9:3) explains that those who argue on Rebbi Yehudah maintain that the meaning of the Neder depends entirely on the way people talk in that particular area where the Neder was made ("Lashon Bnei Adam").
Best wishes,
Mordecai Kornfeld